Document Detail

Comparison of in vivo and in vitro deposition of rhodamine and fluorescein in hair.
MedLine Citation:
PMID:  9763398     Owner:  NLM     Status:  MEDLINE    
A direct differentiation of the internal and external drug-deposition pattern into hair was made using two fluorescent dyes and fluorescence microscopy after systemic administration to mice or external exposure of untreated hair. Mice (23 days old, C57 and Balb/C) were administered either rhodamine or fluorescein intraperitoneally at varied doses on 3 consecutive days of 3 weeks, and hair was sampled 1 week later. Another group was given 10 mg/kg rhodamine or 100 mg/kg fluorescein and sampled at time points from 5 min to 168 hr. The time courses of external deposition of rhodamine and fluorescein into untreated hair were examined after hair was soaked in 0.1 mg/ml solutions at pH 3, pH 6, and pH 9 aqueous buffer or methanol. The hair was then extracted in pH 6 phosphate buffer or methanol for 24 hr. In vivo accumulation was distinguishable as fluorescent bands along the length of the hair for rhodamine and fluorescein. The pattern of in vivo deposition appears to arise from the rapid accumulation within the cortex and medulla, with little deposition evident in the cuticle. Neither phosphate buffer nor methanol washes affected the intensity of fluorescence in the hair. External loading of rhodamine into the hair resulted in staining of the junctions of cuticle scales. This pattern persisted even after 12 hr of solution exposure. Extraction with pH 6 phosphate buffer or methanol did not remove rhodamine. Fluoroscein followed a similar pattern, with maximum fluorescence when hair was loaded in pH 6 100mM phosphate buffer and nominal staining when loaded in pH 9 100 mM Tris buffer or methanol. Soaking the hair in pH 6 buffer, but not methanol, removed some fluorescein. These results demonstrate that compounds in the circulation can rapidly diffuse into the forming cortex and medulla, where rapid associations occur with elongating intermediate filaments specific to the medulla and cortex. These compounds can become significantly occluded within the mature matrix and are resistant to removal in aqueous or methanolic solutions.
P R Stout; J A Ruth
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Drug metabolism and disposition: the biological fate of chemicals     Volume:  26     ISSN:  0090-9556     ISO Abbreviation:  Drug Metab. Dispos.     Publication Date:  1998 Oct 
Date Detail:
Created Date:  1998-11-20     Completed Date:  1998-11-20     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  9421550     Medline TA:  Drug Metab Dispos     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  943-8     Citation Subset:  IM    
Department of Molecular Toxicology and Environmental Health Sciences, University of Colorado Health Sciences Center, Denver, CO 80262, USA.
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MeSH Terms
Fluorescein / pharmacokinetics*
Fluorescent Dyes / pharmacokinetics*
Hair / metabolism*
Mice, Inbred BALB C
Mice, Inbred C57BL
Microscopy, Fluorescence
Rhodamines / pharmacokinetics*
Grant Support
Reg. No./Substance:
0/Fluorescent Dyes; 0/Rhodamines; 2321-07-5/Fluorescein

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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